From 268055dd8ce8314db0c60557c54db02715d5beec Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Sun, 15 Jul 2018 14:52:16 +0000
Subject: [PATCH] [InstSimplify] fold minnum/maxnum with NaN arg

This fold is repeated/misplaced in instcombine, but I'm
not sure if it's safe to remove that yet because some
other folds appear to be asserting that the transform
has occurred within instcombine itself.

This isn't the best fix for PR37776, but it probably
hides the bug with the given code example:
https://bugs.llvm.org/show_bug.cgi?id=37776

We have another test to demonstrate the more general bug.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337127 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/InstructionSimplify.cpp          |  8 +++++++
 .../InstSimplify/floating-point-arithmetic.ll | 24 +++++++------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 87b1fc5b8ee..2eed5fc6418 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -4725,6 +4725,14 @@ static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
           return LHS;
       }
       return nullptr;
+    case Intrinsic::maxnum:
+    case Intrinsic::minnum:
+      // If one argument is NaN, return the other argument.
+      if (match(LHS, m_NaN()))
+        return RHS;
+      if (match(RHS, m_NaN()))
+        return LHS;
+      return nullptr;
     default:
       return nullptr;
     }
diff --git a/test/Transforms/InstSimplify/floating-point-arithmetic.ll b/test/Transforms/InstSimplify/floating-point-arithmetic.ll
index ead4bdbfe5d..afd375f3b13 100644
--- a/test/Transforms/InstSimplify/floating-point-arithmetic.ll
+++ b/test/Transforms/InstSimplify/floating-point-arithmetic.ll
@@ -474,8 +474,7 @@ declare <2 x double> @llvm.maxnum.v2f64(<2 x double>, <2 x double>)
 
 define double @maxnum_nan_op0(double %x) {
 ; CHECK-LABEL: @maxnum_nan_op0(
-; CHECK-NEXT:    [[R:%.*]] = call double @llvm.maxnum.f64(double 0x7FF8000000000000, double [[X:%.*]])
-; CHECK-NEXT:    ret double [[R]]
+; CHECK-NEXT:    ret double [[X:%.*]]
 ;
   %r = call double @llvm.maxnum.f64(double 0x7ff8000000000000, double %x)
   ret double %r
@@ -483,8 +482,7 @@ define double @maxnum_nan_op0(double %x) {
 
 define double @maxnum_nan_op1(double %x) {
 ; CHECK-LABEL: @maxnum_nan_op1(
-; CHECK-NEXT:    [[R:%.*]] = call double @llvm.maxnum.f64(double [[X:%.*]], double 0x7FF800000000DEAD)
-; CHECK-NEXT:    ret double [[R]]
+; CHECK-NEXT:    ret double [[X:%.*]]
 ;
   %r = call double @llvm.maxnum.f64(double %x, double 0x7ff800000000dead)
   ret double %r
@@ -492,8 +490,7 @@ define double @maxnum_nan_op1(double %x) {
 
 define double @minnum_nan_op0(double %x) {
 ; CHECK-LABEL: @minnum_nan_op0(
-; CHECK-NEXT:    [[R:%.*]] = call double @llvm.minnum.f64(double 0x7FF8000DEAD00000, double [[X:%.*]])
-; CHECK-NEXT:    ret double [[R]]
+; CHECK-NEXT:    ret double [[X:%.*]]
 ;
   %r = call double @llvm.minnum.f64(double 0x7ff8000dead00000, double %x)
   ret double %r
@@ -501,8 +498,7 @@ define double @minnum_nan_op0(double %x) {
 
 define double @minnum_nan_op1(double %x) {
 ; CHECK-LABEL: @minnum_nan_op1(
-; CHECK-NEXT:    [[R:%.*]] = call double @llvm.minnum.f64(double [[X:%.*]], double 0x7FF800DEAD00DEAD)
-; CHECK-NEXT:    ret double [[R]]
+; CHECK-NEXT:    ret double [[X:%.*]]
 ;
   %r = call double @llvm.minnum.f64(double %x, double 0x7ff800dead00dead)
   ret double %r
@@ -510,8 +506,7 @@ define double @minnum_nan_op1(double %x) {
 
 define <2 x double> @maxnum_nan_op0_vec(<2 x double> %x) {
 ; CHECK-LABEL: @maxnum_nan_op0_vec(
-; CHECK-NEXT:    [[R:%.*]] = call <2 x double> @llvm.maxnum.v2f64(<2 x double> <double 0x7FF8000000000000, double undef>, <2 x double> [[X:%.*]])
-; CHECK-NEXT:    ret <2 x double> [[R]]
+; CHECK-NEXT:    ret <2 x double> [[X:%.*]]
 ;
   %r = call <2 x double> @llvm.maxnum.v2f64(<2 x double> <double 0x7ff8000000000000, double undef>, <2 x double> %x)
   ret <2 x double> %r
@@ -519,8 +514,7 @@ define <2 x double> @maxnum_nan_op0_vec(<2 x double> %x) {
 
 define <2 x double> @maxnum_nan_op1_vec(<2 x double> %x) {
 ; CHECK-LABEL: @maxnum_nan_op1_vec(
-; CHECK-NEXT:    [[R:%.*]] = call <2 x double> @llvm.maxnum.v2f64(<2 x double> [[X:%.*]], <2 x double> <double 0x7FF800000000DEAD, double 0x7FF8FFFFFFFFFFFF>)
-; CHECK-NEXT:    ret <2 x double> [[R]]
+; CHECK-NEXT:    ret <2 x double> [[X:%.*]]
 ;
   %r = call <2 x double> @llvm.maxnum.v2f64(<2 x double> %x, <2 x double> <double 0x7ff800000000dead, double 0x7ff8ffffffffffff>)
   ret <2 x double> %r
@@ -528,8 +522,7 @@ define <2 x double> @maxnum_nan_op1_vec(<2 x double> %x) {
 
 define <2 x double> @minnum_nan_op0_vec(<2 x double> %x) {
 ; CHECK-LABEL: @minnum_nan_op0_vec(
-; CHECK-NEXT:    [[R:%.*]] = call <2 x double> @llvm.minnum.v2f64(<2 x double> <double undef, double 0x7FF8000DEAD00000>, <2 x double> [[X:%.*]])
-; CHECK-NEXT:    ret <2 x double> [[R]]
+; CHECK-NEXT:    ret <2 x double> [[X:%.*]]
 ;
   %r = call <2 x double> @llvm.minnum.v2f64(<2 x double> <double undef, double 0x7ff8000dead00000>, <2 x double> %x)
   ret <2 x double> %r
@@ -537,8 +530,7 @@ define <2 x double> @minnum_nan_op0_vec(<2 x double> %x) {
 
 define <2 x double> @minnum_nan_op1_vec(<2 x double> %x) {
 ; CHECK-LABEL: @minnum_nan_op1_vec(
-; CHECK-NEXT:    [[R:%.*]] = call <2 x double> @llvm.minnum.v2f64(<2 x double> [[X:%.*]], <2 x double> <double 0x7FF800DEAD00DEAD, double 0x7FF800DEAD00DEAD>)
-; CHECK-NEXT:    ret <2 x double> [[R]]
+; CHECK-NEXT:    ret <2 x double> [[X:%.*]]
 ;
   %r = call <2 x double> @llvm.minnum.v2f64(<2 x double> %x, <2 x double> <double 0x7ff800dead00dead, double 0x7ff800dead00dead>)
   ret <2 x double> %r
-- 
2.50.1